A typical LCD is capable of displaying a clear and sharp image through thousands or even millions of pixels that make up the complete image. The LCD has thus been applied to various electronic equipments in which messages or pictures need to be displayed, such as mobile phones and notebook computers. An LCD panel is a major component of the LCD. The LCD panel generally includes a TFT array substrate, a color filter (CF) substrate opposite to the TFT array substrate, and a liquid crystal layer sandwiched between the two substrates.
FIG. 4 shows part of a typical TFT array substrate 10. FIG. 5 is an enlarged, cross-sectional view of part of the TFT array substrate 10, corresponding to line V-V of FIG. 4.
The TFT array substrate 10 includes a multiplicity of data lines 110 arranged parallel to each other and extending in a same direction, and a multiplicity of gate lines 100 arranged parallel to each other and extending in a direction perpendicular to the data lines 110. Thereby, the data lines 110 and gate lines 100 cooperatively define a multiplicity of pixel regions 180. Each of the pixel regions 180 includes a pixel electrode 140, a TFT 130 arranged at an intersection of a corresponding one of the data lines 110 and a corresponding one of the gate lines 100, a common electrode line 120 parallel to the gate line 100 and being partly overlapped by the pixel electrode 140, and an insulating layer 160 between the pixel electrode 140 and the common electrode line 120.
The TFT 130 includes a gate electrode 131 connected to the gate line 100 for receiving voltage control signals therefrom, a source electrode 132 connected to the data line 110 for receiving display signals therefrom, and a drain electrode 133 connected to the pixel electrode 140 for providing display signals thereto.
The overlapping portion of the pixel electrode 140, the insulating layer 160, and the common electrode line 120 cooperatively form a storage capacitor 150. It is important that the storage capacitor 150 have a larger capacitance for proper displaying of images. In order to display images better, there are two conventional ways for enlarging the capacitance of the storage capacitor 150: enlarging the area of the common electrode line 120, and reducing the thickness of the insulating layer 160. However, an enlarged area of the storage capacitor 150 decreases the aperture ratio of the LCD panel installed with the TFT array substrate 10. Further, the insulating layer 160 cannot be made very thin due to inherent limitations in manufacturing technology.
Accordingly, what is needed is a TFT array substrate for an LCD panel that can overcome the above-described deficiencies.